This gun belongs to my dad, he says he bought it before I was born, ( I'm 43 ). It is a 16 gauge bolt action with a 4 or 5 round clip, well, the clip is missing and we can't find it, does anyone know where we can find one? Serial # is T12506W , it has a 27 inch barrel.

Your father's shotgun is a Marlin Model 55 in 16 gauge. These guns were made for the Canadian market from 1961 to 1963. It sold for $46.25. Finding a magazine for the 16 gauge will be difficult at best as Numrich does not list them. There are a couple of business's advertising magazines in Gun Digest (Gun LIst) so you might want to check with those outfits. Otherwise you will have to search the gun shows in your area.
Good luck.......

Due to the increasing cost of ammunition, there be no warning shot!

The growing federal deficit = generational slavery to the national debt.

I realize this is a very old thread but I thought I would post and see if anyone on this forum knows how many Marlin Model 55 Royal Canadian shotguns were produced. I bought a 12 gauge version of this shotgun on an online auction yesterday and am trying to find out more about them. I have a 336 in .35 Rem, a 980 in .22 magnum, and a 99 .22, all marked Royal Canadian but I wasn't aware of the shotguns until I saw this one on the auction.

There is no information listed for the number of Royal Canadian Model 55 shotguns produced. I can tell you that in 1962, the price of your shotgun was $46.25.
Marlin made two versions of the Levermatic rifles for the Canadian market, the Model 56 and 57 ( & 57M ) to give you a couple of other Royal Canadian guns to look for........

Due to the increasing cost of ammunition, there be no warning shot!

The growing federal deficit = generational slavery to the national debt.